He bases his conclusions on a ten-year study and tests Word's and alternative grammar checkers on the 20 most common grammatical problems from college papers. His conclusions are:

Grammar checkers typically only found 6 or 7 errors out of the 20 errors.

Grammar checkers often offered the wrong advice.

Grammar checkers have not improved their performance since the mid-1990s.

He states: "After ten years of benchmarking the progress of these grammar checking programs, not one of them has made significant improvements toward creating a system that can reliably find and correct the twenty most common usage errors made by first year composition students at American colleges and universities. In ten years of product development, Microsoft, for example, has only managed to improve Word's grammar checking functionality a mere 10%, judging by these test results - small improvement."

Here’s an example of text checked by Microsoft Word. It fails to spot any of the nine errors.

Our research (Editor Software) has shown that anyone reading through a document with grammatical errors will find many more than a computerized grammar checker. I once asked ten people on a writing course to find any grammatical errors in a document. Out of the 25 errors, every participant found over 20 errors and the average found by each participant was 22. In the same document, grammar checkers managed to find 6 out of 25 errors and offered the wrong advice 14 times!

There is no grammar checking software better than that available in Microsoft Word - which is not saying a lot, I know. Why is this so? Because no one is going to invest the huge resources to develop a grammar checker when Microsoft issues one freely to 95 per cent of the computer-user market. And each year Microsoft releases a new version of Word, it offers less and less grammar checking advice.

There are many grammar checkers for sale on the Internet. My view is that they claim far more than they deliver. They check for fewer errors than Microsoft Word's inbuilt grammar checker are simply a standard program bought from companies such as Wintertree.

Companies buy the source code for a grammar checker/spell-checker (designed around 1995) for a couple of thousand dollars, write some unrealistic claims about producing error-free, perfectly written text and sell it for around $75 a copy. They work on people's insecurity over grammar. If you are foolish enough to buy such software, you are getting no more than you already have in your word processor.

Why doesn’t StyleWriter check grammar?

StyleWriter's approach is to assume you can write a grammatically acceptable sentence but constantly encourages you to write clearly and concisely. If you do, you will make far fewer grammatical errors and those you do will be obvious if you read through your text.

StyleWriter has the world's largest database of style faults, plus extensive advice on correct word usage and a few hundred grammatical checks. It is not a grammar checker. We designed the program to teach what people learn on effective writing courses - style, clarity and readability in documents. If you want to proofread for grammatical errors, you need a grammar checker as these are purposely designed to pick up such errors. However, we have yet to find a grammar checker that works as these software programs cannot cope with the intricacies of the English language.